This agreement is done in duplicate.

本协议书一式两份。

They is both in duplicate.

这两者都是一式两份。

This may result in duplicate values.

这可能会导致重复的值。

Please sign the receipt in duplicate.

请一式两份签收这个单据。

This form should be filled out in duplicate.

这种表格要填写一式两份。